When a vehicle, in particular a heavy goods vehicle, rounds a corner, if the speed of the vehicle is sufficiently high, forces on the vehicle during cornering can cause the vehicle wheels on the inside of the curve traveled by the vehicle to lift off the road. Under certain conditions, this can cause the vehicle to overturn. It is therefore known to provide an automatic stability control system which acts to apply the vehicle brakes, and/or control the engine throttle to reduce the speed of the vehicle, when wheel lift is detected, in order to minimise the risk of rollover.
One such system, for a vehicle comprising a tractor and trailer, is disclosed in U.S. Pat. No. 6,176,555. In this prior art system, when it is determined that a situation with potential for rollover exists, for example by monitoring the lateral acceleration of the vehicle, a low-level brake test pulse is applied to the wheels and the ABS control unit is monitored. If the application of the test pulse results in an ABS control intervention, it is deduced that wheel lift has occurred, and a stability control intervention is initiated.